Anaerobic treatment is one of the most effective method using to treat wastewater with high organic pollution level, energy recovery potential, generating less sludge and having the degradability of organic matter up to 75 percent. The research was conducted basing on a anaerobic biolocal reactor UASB with a capacity of 10 liters in the laboratory. Microorganism groups which could be participate in both acid phase and methane phase fermentation, these microorganisms playa avery important and key role in the success of the anaerobic treatment process. Overall, these groups ferment very slowly and are affected by many chemical elements in the environment. In this research, some toxic substances (SO4, Cl-, NH4), which could be inhibit sources of anaerobic microorganisms, were investigated and assessed. The research results showed that at a concentration of SO4 600 mg/l, CI- 10000 mg/l, NH4 800 mg/l with retention time of 72 hours, pH 6.8 - 7.2, the operational efficiency of sources of anaerobic microorganisms reaches the highest efficiency, with leachate taken from landfill Nam Son.